Electron tube with flexible grid supporting structrue



R. F. SPURCK Oct. 29, 1963 ELECTRON TUBE WITH FLEXIBLE GRID SUPPORTING STRUCTURE Filed Sept. 26. 1960- RICHARD F. SPURCK AGENT United States Patent 3,109,119 ELECTRON TUBE WITH FLEXIBLE GRID SUPPORTING STRUCTURE Richard F. Spurck, Wilton, Conn, assignor to The Machlett Laboratories, Incorporated, Springdale, Comm, :1

cooration of Connecticut PP Filed Sept. 26, 1960, Ser. No. 58,295

8 Claims. (Cl. 313-269) This invention relates to improvements in the structure of electron discharge devices and has particular reference to a novel envelope and grid-supporting structure of electron tubes of the type adapted for use within cavities.

More specifically, this invention relates to a grid-supporting structure having spaced cylindrical walls o ned together at one end by a rounded end portion or bight, and having inherent resiliency characteristics enabling it to be readily and easily inserted into a socket.

In tube structures of this type there is provided an annular metal envelope portion or terminal WhlCll provides support for an electrical connection to a grid located internally of the structure. This envelope portion, n known prior art types of electron tubes, is usually a r1g1d or relatively inflexible shape-retaining member having a relatively flat annular end. When inserting such a prior art tube within a tight-fitting socket, the flatended rigid member must be precisely aligned with and carefully guided into the socket in order to mount the tube in proper operating position. In doing so, the operator must not only exercise some degree of skill and care but sometimes is required to expend some time in the process so as not to damage the tube as may occur, for example, by forcing a misaligned tube into a socket.

Another problem in such prior art tube structures is encountered during assembly of the parts of the tube. The annular grid-supporting member and other elements of the tube must necessarily be vacuum-sealed to glass or ceramic portions of the envelope, and in many instances such seals are of a relatively delicate nature and easily ruptured or weakened by exposure to abnormally high temperatures. When locating a grid in predetermined spacial relation to another electrode within the tube, the grid-supporting member is generally adjusted axially with respect to a metal sleeve or the like which is carried by a second non-conducting portion of the envelope. The grid is then fixed in properly adjusted position by brazing the member to the sleeve. This requires localizing a considerable amount of heat in the vicinity of the brazed joint, and in many prior art structures the seal between the member and the glass or ceramic envelope portion is in close enough proximity to the brazed joint as to be damaged by such heat.

Accordingly, it is a primary object of the present invention to provide a novel grid-supporting structure for electron tubes which permits easy and quick insertion of tubes within cavities.

Another object is the provision of an electron tube of the above character wherein the grid-supporting structure is provided with some degree of inherent flexibility which permits slight distortion of the structure when being inserted into a cavity, with the inherent flexibility of the structure permitting the parts to return, after inspection, to their normal prealigned relative positions for proper tube operation.

A further object is to provide such a tube with a gridsupporting structure wherein external brazed joints are located remote from delicate glass-to-metal or ceramic-tometal seals.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawing, wherein there is shown a front elevational view partly in axial section of a tube embodying a preferred form of the invention.

Referring more particularly to the drawing, the depicted tube has a cylindrical metal anode terminal 11 at one end connected by a vacuum seal to one end of a dielectric bulb 12 formed of ceramic or glass. Within the tube and supported by terminal 11 is an axially disposed anode 13.

Located coaxially in predetermined spaced relation to the anode 13 is a disclike cathode emitter 14 which is supported on one end of a cathode support cylinder 15. The opposite end of cylinder 15 is mounted on a tubular cathode terminal 16 which includes an outer tubular member 17 joined to an inner tubular member 18 throughout a considerable portion of their lengths. The inner ends of members 17 and 18 are spaced apart as shown, and the cathode support cylinder 15 is mounted directly upon the spaced inner end of member 17.

The spaced inner end of member 18 carries a metal conductor 19 which supports one end of a filament or heater coil 20. Coil 20 is positioned in close proximity to the adjacent surface of the emitter 14, preferably within a cup-shaped depending portion 21 thereof. The other end of coil 20 is supported by one end of a second conductor 22 extending axially of the tube through a dielectric cylinder 23 which is sealed throughout the outer periphery of its adjacent end to the spaced inner end of member 18. The lower end of conductor 22 is fixed to a transversely disposed metal disc 24 which is sealed throughout its peripheral edge to the inner wall of a second tubular cathode terminal 25. Terminal 25 extends coaxially in spaced relation within terminal 16 and is supported at its inner end by the lower end of the dielectric cylinder 23.

Thus an electrical circuit is completed through the heater coil 20 which, when energized, functions to raise the temperature of the emitter 14, whereupon a copious supply of electrons will be produced. The electrons from the emitter 14 flow to the anode 13 through and under control of a grid 26 in the normal operation of a tube of this type. g

The grid 26, which may be of any selected type such as a mesh or slatted arrangement of wires, is carried by an annular ring 27 which is mounted upon the inner end of a tubular support or sleeve 28 which is provided at its outer end with a flange 29. The flange 29 is turned back upon and spaced outwardly from the major portion of sleeve 28 and is sealed at or adjacent its end to an annular metal envelope portion or ring 30 which is in turn sealed at one end to the dielectric envelope bulb portion 12. Ring 39 extends in closely spaced relation to the sleeve 28 and its inner surface is engaged by a peripheral flange 31, formed on one end of a tubular metal sleeve or guide 32 which is secured to the outer surface of the sleeve 28.

other end by a metal ring 35 to the outer surface of mem-' ber 27.

The upper end of ring wardly extending flange 36 dielectric bulb 12. A similar, but shorter, outwardly extending flange 37 is provided on the lower end of ring 30 and is adapted to interfit within the cylinder formed by the upturned flange 29 on support 28.

When the preassembled cathode-grid structure is mounted as a unit in the tube, the unit is inserted within ring 30 is provided with an outwhich is directly sealed to the I 30 and moved to a position where the grid 26 is spaced the required distance from the adjacent surface of the anode 13. This will cause the upturned flange 29 to embrace the flange 37. on ring 3%). It is to be understood that the extreme end of the upturned flange 29 may extend beyond the end of flange 37, as shown by dotted lines, instead of being on a level therewith, the actual relative positions of these parts depending upon the extent to which the grid-cathode unit is adjusted within the ring 30.

When the unit is properly spaced with respect to the anode, the joint between flanges 29 and 37 is sealed by brazing with a suitable material. It will be noted that this brazed joint is located at a point removed from any other seals, such as the seal between envelope bulb portion 12 and flange 36, and the seals between dielectric ring 34 and support 28 and member 17. Thus, when the braze is made, no heat damage will occur to the other seals.

It will also be noted that the outer end of sleeve 28, which is made of strong but relatively thin, inherently resilient metal, is provided with an inner peripheral recess 38 adjacent the seal with dielectric ring 34 for the purpose of reducing the width of the bight 39 which integrally joins upturned flange 29 with the main portion of sleeve 28, and for decreasing the area of rigid connection between sleeve 28, and dielectric ring 34. In this way added flexibility of the resultant somewhat rounded end of the grid terminal is provided, thus considerably in creasing the ease with which the tube may be quickly and efficiently inserted into a socket. Such flexibility of the structure also is advantageous due to the fact that the flexible flange 29 and bight 39 function to absorb mechanical shocks and vibrations which may occur when the tube is in operative position.

From the foregoing it will be apparent that a novel and improved electron tube structure has been achieved in accordance with the objects of this invention. It is to be understood that modifications may be made in the structure shown and described without departing from the spirit of the invention as expressed in the accompanying claims,

I claim:

1. An electron discharge device comprising an envelope, an'annular metallic member forming part of the envelope, a cylindrical terminal member projecting into the envelope through the annular member, an electrode interiorly of the envelope connected to the cylindrical terminal member, a metallic sleeve within the annular member, a second electrode within the envelope connected to said sleeve, a dielectric ring sealed between the cylindrical terminal member and the sleeve, and resilient means connecting the sleeve to the annular metallic member. I

2. An electron discharge device comprising an envelope, an annular metallic member forming part of the envelope, a cylindrical terminal member projecting into the envelope through the annular member, an electrode interiorly of the envelope connected to the terminal member, a metallic sleeve extending into the envelope within the annular member, a second electrode within the envelope connected to said sleeve, and a dielectric ring sealed between the terminal member and the sleeve, the sleeve being provided at its outer end with an outstanding flange which is turned backupon and overlies the sleeve in substantially parallel spaced relation thereto, said flange being sealed to the annular metallic member.

I 3. An electron discharge device comprising an envelope, an annular metallic member forming part of the envelope, a cylindrical terminal member projecting into the envelope through the annular member, an electrode interiorly of the envelope connected to the terminal member, a metallic sleeve within the annular member, a secat i cud electrode within the envelope connected to said sleeve, a dielectric ring sealed between the terminal member and the sleeve, and an outwardly projecting flange connected with and overlying the sleeve in substantially parallel spaced relation therewith, the annular metallic member having an outstanding peripheral flange which is engaged by and sealed to the flange on the sleeve.

4. An electron discharge device as set forth in claim 3 wherein the flange on the annular member lies within and interfits closely with the flange on the sleeve and is spaced with respect to the end of the flange on the sleeve in accordance with the extent of adjustment of the sleeve axially within the annular member.

5. An electron discharge device comprising an envelope, an annular metallic member forming-part of the being sealed to the annular member adjacent one end,

and a resilient bight connecting the other end of the encircling portion to the outer end portion of the sleeve.

6. An electron discharge device as set forth in' claim 5 wherein the width of the bight is less than the spacing between the sleeve and the overlying encircling'portion.

7. An electron discharge device comprising an envelope, an annular metallic member forming part of the envelope and having an outstanding peripheral .flange at each end, a dielectric ring sealed to the upper flange, a cylindrical terminal member projecting into the envelope through the annular member, an electrode interiorly of the envelope supported upon the terminal member, a metallic sleeve within the annular member and spaced therefrom, a second electrode within the envelope and supported on said sleeve, and a dielectric ring sealed between the terminal member and the outer end' portion of the sleeve, said sleeve being provided at its outer end with a relatively long flange which overlies the sleeve inspaced relation thereto and encircles the flange on the annular member, the end of the flange being sealed to the end of the lower flange on the annular member whereby the seal therebetween is remote from said other seals,

8. An electron discharge device comprising an envelope,'an annular metallic member forming part of the envelope, and having an outstandingflange at one'end, a cylindrical terminal member projecting into the envelope through the annular member, an electrode interiorly of the envelope connected to the terminal member, a metallic sleeve within and spaced from the annular member, a" second electrode within the envelope and mounted on the]v inner end of said sleeve, said second electrode including a second sleeve aflixed to the outer surface of the first sleeve and located in the space between the first sleevemeans connecting the first sleeve to the annular metallicmember.

References Cited in the file of this patent UNITED STATES PATENTS Beggs Feb. 25, 1947 Eitel Aug. 3, 1948 

1. AN ELECTRON DISCHARGE DEVICE COMPRISING AN ENVELOPE, AN ANNULAR METALLIC MEMBER FORMING PART OF THE ENVELOPE, A CYLINDRICAL TERMINAL MEMBER PROJECTING INTO THE ENVELOPE THROUGH THE ANNULAR MEMBER, AN ELECTRODE INTERIORLY OF THE ENVELOPE CONNECTED TO THE CYLINDRICAL TERMINAL MEMBER, A METALLIC SLEEVE WITHIN THE ANNULAR MEMBER, A SECOND ELECTRODE WITHIN THE ENVELOPE CONNECTED TO SAID SLEEVE, A DIELECTRIC RING SEALED BETWEEN THE CYLINDRI- 